Three years ago, of course, Scott Brown rode his pickup truck to an unexpected victory in a race that signaled the building GOP momentum in the 2010 midterm elections.

And if Kerry does get picked (at this point, this still seems to be a trial balloon), you can bet Brown's name would quickly rise to the top -- along with a slew of ambitious Democrats -- among prospective candidates for the special election.

Massachusetts's two Senate seats were long held by Kerry and Sen. Ted Kennedy (D-Mass.) until Kennedy's death in 2009. That means there are lots of candidates -- mostly Democrats -- who have been patiently waiting for their chance to step up.

Among those most likely to make the race:

* Brown: He's holding a news availability Tuesday at 5 p.m. Eastern, where he's likely to be asked about the potential special election. Make no mistake: In Massachusetts, it's hard to see other Republicans having a good chance for this seat without Brown. Of course, nobody saw Brown as a strong candidate when he first ran in 2010. Asked about Brown's plans, aides pointed to the news conference Tuesday. One reason he wouldn't run: Whoever wins would have to run for a full term in 2014, which would mean that Brown would set himself up to run four high-profile Senate campaigns in just five years if he won. That's A LOT.

* Attorney General Martha Coakley (D): She took lots of blame for her loss to Brown in 2010 (think: shaking hands in the cold at Fenway Park, Curt Schilling is a Yankees fan, and her ill-fated pre-election vacation), but remains one of the most popular politicians in Massachusetts, according to a recent Boston Globe poll. Redemption time?

* Rep. Michael Capuano (D): He lost to Coakley in the primary for the 2010 race and was rumored as a potential Brown challenger this year. He didn't raise money like someone ramping up for another Senate campaign this cycle, though, and has $500,000 cash on hand.

* Rep.-elect Joe Kennedy III (D): Yes, it would be hard for Kennedy to launch a Senate campaign before he was even sworn into Congress (or even shortly thereafter), but this is a Kennedy we're talking about. And he's 32-years-old, which is actually older than Uncle Ted was when he first won his seat. And if his House race is any sign ($4 million raised), "JK3" could easily raise the funds quickly. (Side note: If the well-funded Brown runs, Democrats will want a fundraising juggernaut to run against him.)

* Rep. Ed Markey (D): Often mentioned as a potential Senate candidate, he passed on the 2010 race and on challenging Brown in 2010. But with Republicans looking a good bet to hold the House for a little while, maybe Markey gives up on trying to become a chairman again and takes the plunge. He had $3.2 million cash on hand at last check, which is a healthy start.

* Gov. Deval Patrick (D): The two-term governor has said he will not run for a third term in 2014 and has very good approval and favorability ratings in recent polls. He gained acclaim at the Democratic National Convention when he told his fellow Democrats to "grow a backbone," and he would also be running to be the only black senator. But his state has a pair of medical scandals unfolding, he has said he would serve out his term as governor, and he's also been rumored as a potential Cabinet pick for Obama (Attorney General?). Additional intrigue: Patrick had dinner with Obama at the White House on Friday.

* Marty Meehan (D): The former congressman left the House in 2007 to become chancellor of the University of Massachusetts Lowell and passed on running in 2010 and 2012. Still, he's got $4.8 million in the bank, which is more than just about anybody else in the House. But he has already said he wouldn't run if the Kerry seat is vacant. "I’m not running for anything,” Meehan said in August. “I would never walk away from this place now. There’s too much left to be done, and I’m going to finish.”

* Richard Tisei (R): This might be the GOP's backup plan. Tisei, a former state senator, ran a tough campaign against Rep. John Tierney (D-Mass.) in a Democratic district this year and nearly won.

* Setti Warren (D): The Warren before The Warren, the Newton mayor was emerging as the frontrunner in a weak Democratic Senate primary field before Elizabeth Warren came along in 2011. He soon cleared the way, though, and probably built up some goodwill because of it. The question is whether he convinced Democrats that he's ready for the big time.

* State Sen. Ben Downing (D): The 31-year old state senator, who has been in office since 2006 and chairs the Telecommunications, Utilities and Energy Committee, is likely to run for the seat if it comes open. Downing is also a former aide to Massachusetts Reps. Bill Delahunt, Richard Neal, John Olver.

Now, for the specifics of the special election:

Patrick is responsible for picking the dates of the primary and special elections, with the latter being held within 160 days of the vacancy being declared. That could put the race in mid-2013 or later, depending on when Kerry vacated the seat.

The primary must be held six weeks before the special election.

There would also be an appointment before the special election. In 2009, Patrick appointed Paul Kirk as a caretaker and said that whoever fills that slot should be someone who will not run in the special election.

And as we noted above, whoever wins would have to run again in 2014, when the seat is up for a full term.

Updated at 1:16 p.m.

Aaron Blake covers national politics and writes regularly for The Fix.

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